Studies On The Biological Character And Controlling Effects On Aphids Of Scymnus (Neopullus) Babai Sasaji

Laboratory experimentation and field observation were conducted to research the biological characteristics and life table of laboratory population of S. (Neopullus) babai Sasaji, and its functional response and control effects on A. glycines were determined. The results were shown as follows:First, we investigated the developmental durations, of S. (Neopullus) babai Sasaji in conditions of constant temperatures, and we also determined its developmental threshold temperature and effective accumulated temperature. The developmental duration of the ladybug decreased with the temperature increasing from 19℃to 31℃, and egg-adult durations are from 32.88d at 19℃to 14.37d at 31℃. The low threshold of developmental temperature for the egg, larval, pupa and egg-adult of the ladybug were 13.50℃, 11.01℃,12.02℃and 10.91℃respectively, and the effective accumulative temperature for the egg, larval, pupa and egg-adult were 58.53,97.37, 113.42 and 294.59 day-degrees respectively.Second, we determined the impacts of temperature and photoperiod on the reproduction and longevity of S. (Neopullus) babai Sasaji. Results of correlative analysis showed that the development and longevity of S. (Neopullus) babai Sasaji were significantly impacted by temperature. The most suitable temperature and photoperiod were 28℃and 14 hours for reproduction, and they were 25℃and 12 hours for vitality.Third, we established the life table of laboratory population of S. (Neopullus) babai Sasaji. Mortalities rate of egg, 1st～4th instars larvae, and pupae were 56.2%,28.6%, 6.1%,6.5%,0, and 35.7% respectively. The trend index of the population was 6.7890. In the laboratory conditions, the intrinsic rate of natural increase was 0.089, the average generation was 73.784d, and the index of population trend was 9.Four, we evaluated the functional response of S. (Neopullus) babai Sasaji to A. glycines. The functional response of S. (Neopullus) babai Sasaji fitted the models of HollingⅡwell in different density of A. glycines. Daily theoretical maximum predatory capacities of 1st～4th instars larvae and adults were 44.0119,92.0403, 112.8878,173.9130 and 32.6797. Daily predatory capacities of 1st～4th instars larvae and adults increased with increasing temperature, and at 31℃, their predatory capacities were the greatest.Five, we studied the control capabilities of S. (Neopullus) babai Sasaji on A. glycines within cages in laboratory. The results showed that the control effects were 100% in nine days when the ratio of the adult ladybugs (♀:(?)= 2:1) and aphids was more than 1: 10; the control effects were 100% in six days when the ratio of the larvae of ladybugs and aphids was more than 1:10.Six, we also studied the control capabilities of S. (Neopullus) babai Sasaji on A. glycines within cages in the soybean field. The results showed that the control effects were 100% in nine days when the ratio of the adult ladybugs (♀:(?)= 2:1) and aphids was more than 1:10; the control effects were 100% in six days when the ratio of the larvae of ladybugs and aphids was more than 1:10.